我在从 firestore 获取数据时遇到问题,代码如下:-
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:flutter/material.dart';
import 'package:machineweb/model/models.dart';
class ProductArgs {
String crop;
ProductArgs({this.crop});
}
class ShowProduct extends StatefulWidget {
static String route = '\showproductroute';
@override
_ShowProductState createState() => _ShowProductState();
}
class _ShowProductState extends State<ShowProduct> {
@override
Widget build(BuildContext context) {
double screenWidthSize = MediaQuery.of(context).size.width;
double height = MediaQuery.of(context).size.height;
ProductArgs args = ModalRoute.of(context).settings.arguments;
FirebaseFirestore firestore = FirebaseFirestore.instance;
List<DocumentSnapshot> products = []; // stores fetched products
bool isLoading = false; // track if products fetching
bool hasMore = true; // flag for more products available or not
int documentLimit = 2; // documents to be fetched per request
DocumentSnapshot
lastDocument; // flag for last document from where next 10 records to be fetched
ScrollController _scrollController = ScrollController();
print(args.crop);
getProducts() async {
if (!hasMore) {
print('No More Products');
return;
}
if (isLoading) {
return;
}
setState(() {
isLoading = true;
});
QuerySnapshot querySnapshot;
if (lastDocument == null) {
querySnapshot = await firestore
.collection('productData')
.where('type', isEqualTo: args.crop)
.limit(documentLimit)
.get();
} else {
querySnapshot = await firestore
.collection('productData')
.where('type', isEqualTo: args.crop)
.startAfterDocument(lastDocument)
.limit(documentLimit)
.get();
print(1);
}
if (querySnapshot.docs.length < documentLimit) {
hasMore = false;
}
lastDocument = querySnapshot.docs[querySnapshot.docs.length - 1];
products.addAll(querySnapshot.docs);
setState(
() {
isLoading = false;
},
);
}
_scrollController.addListener(
() {
double maxScroll = _scrollController.position.maxScrollExtent;
double currentScroll = _scrollController.position.pixels;
double delta = MediaQuery.of(context).size.height * 0.20;
if (maxScroll - currentScroll <= delta) {
getProducts();
}
},
);
int _crossAxisCount = 0;
if (screenWidthSize > 720) {
_crossAxisCount = 3;
} else if (screenWidthSize > 520) {
_crossAxisCount = 2;
} else {
_crossAxisCount = 1;
}
print(products.length.toString());
return Container(
child: Column(children: [
Expanded(
child: products.length == 0
? Center(
child: Text('No Data...'),
)
: ListView.builder(
controller: _scrollController,
itemCount: products.length,
itemBuilder: (context, index) {
return ListTile(
contentPadding: EdgeInsets.all(5),
title: Text(products[index].data()['name']),
subtitle: Text(products[index].data()['short_desc']),
);
},
),
),
isLoading
? Container(
width: MediaQuery.of(context).size.width,
padding: EdgeInsets.all(5),
color: Colors.yellowAccent,
child: Text(
'Loading',
textAlign: TextAlign.center,
style: TextStyle(
fontWeight: FontWeight.bold,
),
),
)
: Container()
]),
);
}
}
即使 firestore 上有数据,products.lenght
也为零。
这是我的index.html
:-
<script src="https://www.gstatic.com/firebasejs/8.3.1/firebase-auth.js"></script>
<script src="https://www.gstatic.com/firebasejs/8.3.1/firebase-firestore.js"></script>
<script src="https://www.gstatic.com/firebasejs/8.3.1/firebase-analytics.js"></script>
<script src="https://www.gstatic.com/firebasejs/8.3.1/firebase-storage.js"></script>
甚至尝试将其更改为:-
<script src="https://www.gstatic.com/firebasejs/7.20.0/firebase-storage.js"></script>
如何从 firestore 获取数据,我尝试使用其他软件包,即使不起作用。
有什么解决方案吗,有很多类似的问题,但不是通过问题来解决?
最佳答案
这可能是因为您忘记添加 Firestore 规则以允许从您的集合中进行提取。我建议您检查一下获取快照是否出错。您可以通过添加到代码中来做到这一点:
if (snapshot.hasError) { print(snapshot.error.toString()) }
关于firebase - Flutter web无法从firestore获取数据,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/67173175/